Types and Uses of DesiccantsA desiccant is a substance that absorbs water vapor from the air. Typically used in thepackaging industry, desiccants are used to eliminate the harmful humidity that couldpotentially degrade or even destroy products that are sensitive to moisture. The 3 mostcommonly used desiccants include:1. Silica Gel DesiccantsSilica gel is a granular form of silica that is made synthetically from sodium silicate. It isnon-hazardous and can absorb upwards of 40% of its weight in water vapor at 100%humidity. It is a solid substance that is extremely porous, making it capable of absorbinghigh levels of moisture, it has the highest moisture adsorption capacity of any commercialdesiccant making it one of the most effective ingredients for products designed toprevent corrosion during transportation and storage.In cases where moisture needs to be eliminated entirely, the use of powerful desiccantssuch as silica gel may not be enough. To that end, moisture barrier bags can provide thelevel of protection required. When used in conjunction with silica gel, the levels ofmoisture can be reduced to infinitesimal levels. The use of indicating silica gel can alsobe a great help, it is a simple yet effective way to ensure that moisture levels remain at aminimum. Not only does indicating silica gel absorb surrounding moisture, it alsochanges colors as it does so. The more moisture the silica gel absorbs, the less effective iteventually becomes. Once it reaches its saturation point, indicating silica gel will turn to aspecific color, signaling it should be replaced.2. Molecular Sieve DesiccantsMolecular Sieve is the most aggressive of the primary desiccants and our first choice forthe most demanding and unique applications. A distinctive feature of this non-hazardoussynthetic product is our ability to control the uniformity of pore size openings during themanufacturing process.This yields selective adsorption characteristics that can be very useful drying packageswithout removing other desirable molecules, such as volatile organics that might bepresent in the package. Molecular sieve can hold moisture to temperatures well past450°F (230°C) and, because of its high affinity for moisture, can bring the relativehumidity in packages down as low as 10%.3. Montmorillonite Clay DesiccantsMontmorillonite Clay is the least expensive of all desiccants and is a naturally occurringnon-hazardous mineral composed of magnesium aluminum silicate (a calcium aluminumsilicate type of hydros clay).Montmorillonite Clay is used in most industrial applications requiring humidity controlbecause it recharges easily and does not swell as it adsorbs water vapor. Subject to adegree of variability for being a natural material, clay desiccant will adsorbapproximately 25% of its weight in water vapor at 77º F and 40% relative humidity.
This desiccant works well at low and room temperatures, but has a rather low ceilingtemperature. At 120º F montmorillonite clay will begin to desorb or shed the moisture ithas adsorbed, an important consideration for storage in hot areas.Desiccants on their own can be extremely effective, although they work better when usedin combination with moisture barrier bags. Different moisture barrier bag materials comewith different MVTR ratings. These ratings are extremely important, as they are the onlyreference point when it comes to the amount of moisture that can seep in over a period oftime. Currently, the most effective moisture barrier bag material has an MVTR rating of0.02, meaning that only 0.02 grams of moisture can penetrate the material over a 24-hourperiod in 95 percent humidity.Proper protection from moisture is important. To that end, combining moisture barrierbags with a desiccant is one of the most efficient ways to protect your goods. No matterhow effective a moisture barrier bag may be, there is always a possibility that a minuteamount of moisture may seep in. The use of desiccants is a smart preventive measure foradded protection.About Protective PackagingProtective Packaging specializes in protecting products, equipment, and machinery fromcorrosion, electrostatic discharge, contaminants, ultraviolet rays and dust during shippingand storage. Our corrosion prevention products and services consist of: anti-static andstatic shielding bags, flexible packaging materials, moisture barrier bags, Mil-Spec(military specified) packaging materials, corrosion inhibitors, desiccants, humidityindicator devices, on-site packaging, packaging consulting, and custom-made packaging.For more information, please visit http://www.protectivepackaging.net